Water vapor (steam) is used in various industries (e.g., plant industry, machine (mechanical) industry, food industry, and medical industry) for power generation, sterilization, cleaning (washing), and the like. A seal material (e.g., rubber O-ring) is used for a pipe and a device in which water vapor flows, and prevents water vapor from flowing to the outside.
In recent years, there has been a tendency that the temperature of water vapor used in power plants is increased in order to improve the power generation efficiency. Therefore, high-temperature water vapor resistance has been desired for a seal material. In such a case, a seal material formed of a crosslinked fluoroelastomer (e.g., fluororubber or perfluororubber) is used. However, a seal material formed of a crosslinked fluoroelastomer may exhibit poor vapor resistance, and a further improvement has been desired (see Patent Literature 1, for example).
A crosslinking agent is used when producing a crosslinked fluoroelastomer, and various crosslinking agents have been known. For example, triallyl isocyanurate (TAIC) is generally widely known (see Patent Literature 2 to 6, for example), and divinylbenzene (see Patent Literature 2 to 5, for example), divinylbiphenyl (see Patent Literature 5, for example), and the like are also known.
However, a novel crosslinking agent that can further improve the heat resistance and the vapor resistance of a crosslinked fluoroelastomer has been desired.
Patent Literature 6 discloses tetrafluoroethylene and a perfluoroalkyl vinyl ether as a raw material monomer for producing a fluoroelastomer.
Non-Patent Literature 1 discloses 1,2,2-trifluorostyrene (perfluorovinylbenzene) as a material for producing a fuel cell separation membrane.